There are countless devices for introducing a catheter within a patient for infusion or extraction of fluids. One class of such devices includes a catheter assembly having a catheter, which can be of an extended length, an insertion needle and a winged catheter inserter. As with conventional catheter placement kits, the insertion needle is positioned within the interior of the catheter, with the tip of the needle extending out of the tip of the catheter. In such a device, the proximal end of the catheter usually terminates at a hub. A wire is attached to the needle and threaded through the interior of the catheter. The wire terminates at a knob which is removably attached to the hub.
Near the distal end of the catheter and needle is an inserter. The inserter is commonly an inserter having a wing structure similar to that widely used in the catheter art. Disposed through the center of the inserter is a guide channel. The catheter and needle are placed within the interior of the guide channel and pass through the interior of the inserter.
A sheath is placed around the exterior of the catheter over the length of the catheter running from near the inserter to the hub. The sheath is splittable. For instance, the sheath is weakened or has a partial slit along its longitudinal axis. During operation, as the sheath is pulled forward, the catheter within the sheath is also moved forward. This allows the catheter to be inserted into a patient by simply pulling the sheath forward. At the same time, the sheath is opened along its slit and removed from the cannula by sheath stripping means located distal of the inserter structure. Thus, the sheath is split and removed from about the cannula prior to the time the cannula travels through the inserter and into the patient.
A problem faced with catheter assemblies using a splittable sheath is how to securely lock the sheath once the catheter has been properly positioned within the patient. One known device for locking a splittable sheath is disclosed in U.S. Pat. No. 4,840,613 to Balbierz. This patent discloses a two-piece locking mechanism. The locking mechanism includes a first locking member carried by the inserter and a slidable second locking member located about the sheath between the inserter and the hub. The first and second lock members are interlockable with one another. The locking mechanism is used to secure the sheath and catheter in place once they are advanced to the desired location.
The first and second lock members are manufactured with sufficiently close tolerances such that when locked together, they sandwich or compress the sheath within their joined structure to restrict movement of the sheath.
It would be an advancement in the art to provide a simple, yet effective sheath lock which allows the sheath to be easily pulled to properly position the catheter and also allows the sheath to be securely locked into any such desired position.
Such a sheath lock is disclosed and claimed herein.